Method for lifting a manhole cover

Abstract

A method and apparatus are disclosed for lifting a manhole cover. The apparatus comprises a means for engaging the manhole cover which cooperates with a means for raising and lowering the manhole cover. A pivot means is also provided which cooperates with the means for raising and lowering the manhole cover. According to the method of the invention the pivot means is positioned adjacent one edge of the manhole cover. A lifting means is engaged with the manhole cover and a bar is placed in engagement with the pivot means and the lifting means. Pressure is applied to one end of the bar and the manhole cover is lifted to a position to allow pivoting the manhole cover to a desired position prior to lowering.

Description

BACKGROUND OF THE INVENTION

This invention relates to manhole covers and, more particularly, to a method and apparatus for raising and lowering manhole covers.

Prior to our invention, it was customary for one person to use a pick to wedge open or pry up one edge of the manhole cover. A second person would then grab the partially raised cover and hold it until his partner could also help him move the cover.

Some covers can weigh up to about 400 pounds and many serious injuries have resulted from this method of handling manhole covers. To the best of our knowledge, the only attempt to overcome the hazards and difficulties associated with handling manhole covers has been the use of a chain fall secured to a tripod. However, this arrangement did not provide a convenient way of pivoting the cover to a desired final position. For this reason and because it is cumbersome, the arrangement has received very little acceptance by industry.

BRIEF SUMMARY OF THE INVENTION

The apparatus comprises a means for engaging the manhole cover which cooperates with a means for raising and lowering the manhole cover. A pivot means is also provided which cooperates with the means for raising and lowering the manhole cover. According to the method of the invention the pivot means is positioned adjacent one edge of the manhole cover. A lifting means is engaged with the manhole cover and a bar is placed in engagement with the pivot means and the lifting means. Pressure is applied to one end of the bar and the manhole cover is lifted to a position to allow pivoting the manhole cover to a desired position prior to lowering.

OBJECTS OF THE INVENTION

It is therefore the primary object of our invention to provide a method and apparatus for raising and lowering a manhole cover that requires only one person to operate.

Another object of our invention is to provide a method and apparatus for pivoting the manhole cover to any desired position.

Still another object of our invention is to provide a method and apparatus that eliminates handling the manhole cover by hand thereby reducing a safety hazard.

Yet another object of our invention is to provide an apparatus that is lightweight and economical to produce.

A further object of our invention is to provide an apparatus which can be adapted for use with present manhole covers.

Still yet another object of our invention is to provide method and apparatus to prevent the manhole cover from slipping on the lifting lever.

These and various other objects and advantages of our invention will become apparent when taken in conjunction with the following description and the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevation view partially in cross section showing the preferred embodiment of our invention.

FIG. 2 is an enlarged view showing our preferred means for engaging the manhole cover.

FIG. 3 is an enlarged view showing our preferred pivot means.

FIG. 4 shows our preferred lever for raising and lowering the manhole cover.

FIG. 5 is an elevation view partially in cross section showing alternative embodiments for means to engage the manhole cover, means to pivot and a lever for raising and lowering the manhole cover.

FIG. 6 is an elevation view partially in cross section showing another alternative embodiment for means to engage the manhole cover.

FIG. 7 is an elevation view partially in cross section showing a further alternative embodiment for means to engage the manhole cover and lever for raising and lowering the manhole cover.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Now refer to FIGS. 1 through 4 wherein like numerals refer to similar parts throughout the several views. According to our invention we provide a means generally designated as 100 for engaging the manhole cover 2. A lever means generally designated as 110 to cooperate with the means for engaging the manhole cover 2, for raising and lowering the manhole cover, and a pivot means generally designated as 120, which cooperates with the means for raising and lowering the manhole cover 2.

The means, generally designated as 100, for engaging the manhole cover 2 comprises a pad 4, of any desired shape, having a width W which is slightly less than a width W, of an opening 6 in the manhole cover 2. Secured near one edge of the pad 4 is an eyebolt 8. Eyebolt 8 can be welded to the pad 4 or preferably threaded as shown in FIG. 2. A bushing 12, having a width W2 also slightly less than the width W, of opening 6 is in manhole cover 2, is circumferentially slidably mounted on the shaft of eyebolt 8. It will be understood that the bushing 12 may be provided in a variety of sizes to accommodate different size openings 6 in manhole covers 2, thus the reason for preferably threading eyebolt 8 into pad 4. When eyebolt 8 is threaded into pad 4 the shaft should have a length L at least equal to a length L, of pad 4 plus two times a length L2 of bushing 12.

The lever means, generally designated 110, for raising and lowering the manhole cover 2 comprises a bar 14 which preferably has an adjustable stop means 16 mounted thereon and adapted to abut the means 100 for engaging the manhole cover 2 at a predetermined location on the bar 14. Stop means 16 prevents manhole cover 2 sliding on bar 14 during lifting.

Pivot means, generally designated 120, comprises a base 18 having a cylindrical tube 20 mounted thereon. A pivot member 22, preferably a pipe, is mounted for pivotal movement inside cylindrical tube 20. A bearing 24 is preferably mounted inside tube 22 and adapted to contact the base 18 and the lower surface of pivot member 22 so that pivot member 22 is prevented from contacting base 18. A means, generally designated 26, is secured adjacent the top of the pivot member 22 and is adapted to be engaged by the means, generally designated 110, for raising and lowering the manhole cover 2. We prefer a generally U-shaped saddle 28 be secured to the top of pivot member 22. The saddle 28 has bars 30 secured to the generally upstanding legs of saddle 28 to prevent spreading of the legs. Pins 32 may be provided on base 18 to prevent base 18 from slipping when used on a hard surface such as asphalt or concrete. A handle 34 could also be provided to facilitate carrying pivot means 120. In addition, a wing nut 36 could be used to prevent pivot member 22 from moving inside tube 20 while carring pivot means 120.

In operation, pivot means 120 is positioned adjacent one edge of manhole cover 2. Lifting means 100 is engaged in manhole cover 2 through opening 6. The bar 14 is placed through eyebolt 8 and a first end is positioned in saddle 28. Pressure is applied by lifting on the second end thereby bringing the upper surface of pad 4 into contact with a portion of the lower surface of manhole cover 2 adjacent opening 6. Continuing to lift until the manhole cover 2 is above ground level and then pivoting the manhole cover to a desired position. The manhole cover 2 is then lowered to the ground level.

In replacing the manhole cover pressure is again applied by lifting on the second end of bar 14 until manhole cover 2 is above ground level then pivoting the manhole cover over the opening in the manhole and lowering the cover over the opening.

ALTERNATIVE EMBODIMENTS

Refer now to FIGS. 5 through 7 for an understanding of various alternative embodiments. One means we provide for engaging the manhole cover 2 is with a ring 50 secured thereto such as by a block 52. It should be understood that block 52 could be welded to or threaded into manhole cover 2.

Another means for engaging manhole cover 2 is a sissor type, generally designated 60, which comprises a pair of bars 62 pivotally secured together by a pin 64. Bars 62 have a leg 66 adapted to engage the outer edges of manhole cover 2 and a pair of legs 68 adapted to receive a means for raising and lowering the manhole cover 2.

Still another means for engaging manhole cover 2 is a ball 70 having a stem 72 adapted to be welded to or threaded into manhole cover 2.

An alternate pivot means, generally designated 80, comprises a base 82, a support 84 mounted on the base 82 and a ball joint 86 secured adjacent the top of the support 84 for engagement with means for raising and lowering manhole cover 2.

According to one alternate for the means for raising and lowering the manhole cover 2, we provide a hook 90 on a first end of bar 14. Bar 14 in this embodiment is adapted to rest on pivot means 80 or 12 by securing a cup-shaped member 90 thereto. Pressure is applied by pushing downward on the second end of bar 14 to raise the manhole cover 2.

In still another embodiment bar 14 is adapted to engage the ball 70 of the ball-type joint by having a socket 101 which can be secured to a first end of bar 14 if it is desired to apply pressure by pushing to raise manhole cover 2, or it can be secured away from the ends of bar 14 if it is desired to apply pressure by lifting to raise manhole cover 2.

While we have described our preferred and various alternate embodiments of our invention, it will be understood by those skilled in the art that various other alternatives and combinations of our invention can be practiced and we intend only to be bound by the scope of the appended claims.

Claims

1. A method of raising and lowering a manhole cover from a manhole comprising the steps of:

a. positioning a pivot means adjacent one edge of said manhole cover, said pivot means being stationary with respect to said one edge of said manhole cover;

b. providing a means for engaging said manhole cover near the center so that said manhole cover will be raised generally vertical with respect to ground level, said means for engaging said manhole cover comprises a pad, having a width w slightly less than a width w₁ of an opening near the center of said manhole cover, said pad having a lifting means secured near one edge, and said lifting means having a bushing slidably mounted thereon, said bushing having a width w₂ slightly less than said width w₁ of said opening in said manhole cover;

c. inserting said pad and a portion of said lifting means through said opening in said manhole cover;

d. centering said portion of said lifting means in said opening so that said bushing slides into the annulus formed by said opening and said portion of said lifting means;

e. placing a lever in bearing engagement with said pivot means and in lifting engagement with said lifting means;

f. applying pressure to one end of said lever to bring the top of said pad into contact with the bottom of said manhole cover and continuing to apply pressure until said manhole cover is above said ground level;

g. pivoting said manhole cover to a desired position; and

h. lowering said manhole cover to said ground level by releasing said pressure applied to said one end of said lever.

2. A method according to claim 1 including the additional steps of:

a. after step (g) repeating step (f);

b. pivoting said manhole cover over the opening in said manhole; and

c. lowering said manhole cover to its final resting place.

3. A method according to claim 2 including the additional step of placing a stop means in contact with said lifting means to prevent said lifting means from slipping on said lever so that said manhole cover will be automatically aligned with said opening in said manhole.